27-08-2017, 08:14 PM
(This post was last modified: 27-08-2017, 08:15 PM by Murphyv310.)
Hi.
Well I discovered that on SSB there was something amiss. The drift was grim, even walking on the shed floor it went haywire. The issue though was simple, the KTW61 local oscillator valve had come unstuck from its base. a quick NOS replacement effected a cure.
I also found the C83 was missing, this I noticed by hand capacitance issues when trying to set up the local oscillator.
Next thing to show up was intermittent loss of gain. This took a bit of searching, I eventually took off the screening can under the AF amp and BFO to find two badly leaking 0.1uf alloy can caps. I re-stuffed the three caps that live in the can, again much improved performance.
There are about half a dozen of these caps left, all of them leak to an extent and all read high, between 0.15 to 0.2uf, this increase in value is common enough on radios of this age but leakage on AGC lines isn't good.
Well I discovered that on SSB there was something amiss. The drift was grim, even walking on the shed floor it went haywire. The issue though was simple, the KTW61 local oscillator valve had come unstuck from its base. a quick NOS replacement effected a cure.
I also found the C83 was missing, this I noticed by hand capacitance issues when trying to set up the local oscillator.
Next thing to show up was intermittent loss of gain. This took a bit of searching, I eventually took off the screening can under the AF amp and BFO to find two badly leaking 0.1uf alloy can caps. I re-stuffed the three caps that live in the can, again much improved performance.
There are about half a dozen of these caps left, all of them leak to an extent and all read high, between 0.15 to 0.2uf, this increase in value is common enough on radios of this age but leakage on AGC lines isn't good.
